LONDON, England (CNN) --The CIA official in charge of looking for weapons of mass destruction in Iraq is briefing American lawmakers Thursday, but U.S. officials do not expect him to reveal any "smoking gun."

CNN Anchor Becky Anderson spoke to Garth Whitty, from Royal United Service Institute and a former UNSCOM weapons inspector:

Q. Are you surprised by the apparent absence of WMD in Iraq?

A. Certainly not surprised they haven't found anything relating to a new program. A little surprised that there's been no residue from the original program... from the 1980s. Much of that was destroyed but nevertheless there must be some residue left in Iraq.

Q. Why is there no evidence?

A. I don't know – perhaps they're starting at the wrong places. Obviously intelligence is not as good as it should be. Perhaps the biological and chemical weapons experts don't know how to search... there's a difference between being an expert in those fields and finding something that's hidden.

Q. What do you think will be the fallout for the Bush administration and UK Prime Minister Tony Blair if no WMD is found or no evidence?

A. It's a major setback for the governments but they will say, rightly, that they were acting on the best intelligence they had. The reality was that the WMD program was enormous. Much of it was used on Iranians and Kurds. Much was destroyed by Iraqis in the aftermath of the 1991 war and more of it was destroyed by U.N. Special Commission but that with a program of that size it's inconceivable there isn't somewhere, something that was left behind.

Q. So where is it?

A. Where it is is the problem. It may be on some of the sites and buried, it may have been deployed into the field and forgotten about. Iraq is a large country but when you think that the United Kingdom got rid of its own chemical weapons program in the late 1950s and it's still a regular, if not frequent, occurrence for chemical weapons to be found in this country... then it's inconceivable that there aren't chemical weapons in Iraq.

Q. It's reported that of the $87 billion that Bush is asking of Congress for the rehabilitation and costs of war in Iraq and Afghanistan, $1bn of that will be spent on the search for WMD. Is that a waste of money?

A. It's a lot of money but not a waste... but it would be ironic in the extreme if the residue of the old program were to fall into the hands of terrorists for example. One of the arguments for war with Iraq was they were providing or might provide WMD to terrorist organizations. And if that were to happen after the war that would be unacceptable.

Had it happened though I think we would have heard something about it. Nevertheless there's a strong case for continuing to look for WMD and remove that possibility.

Q. What happens next – how much deeper, how much wider, how much longer do experts search for?

A. They've got to revisit the sites. There must be a great deal of information. The most powerful intelligence agencies in the world have been arrayed against Iraq for a long time, and they've got to go back over everything and make sure they're not missing things.

The other surprise, I think, is that none of the key Iraqis involved in the program have given information that is of value, and I think that has to be revisited as well.

Q. How sympathetic are you, as an ex-weapons inspector, that many in U.S. and UK are now highly skeptical of the justification given for war?

A. On the basis of the information in the public domain, the case for a new military capability in terms of WMD was a very weak one. That doesn't mean to say there wasn't stronger intelligence we didn't get to see. There's a quantum difference between research and development which Iraqis may have been undertaking and actually having a military capability that presented a clear and present danger.